What is A Mechanical Seal?

Author:Site Editor     Publish Time: 2021-05-27      Origin:Site

If you are looking to buy or source custom mechanical seals, you are in the right place. We aim to help you understand everything you will ever need to know about mechanical seals. So, let's begin. 


What is A Mechanical Seal? 


You can't understand the application and functionality of a mechanical seal unless you know what it is. In simple terms, it is a device that seals the pumped fluid inside the pump casing. It uses a rotating shaft and a pump seal to keep the pumped item such as oil, water, etc., inside. 


A mechanical seal also aims to reduce the loss of the pumped item and costs avoided with leakages. Since their inception in the 1900s, these seals have eliminated gland packings that were incredibly costly. A mechanical seal will be installed where the pump shaft leaves or enters the casing. 


mechanical seals application-1

How it Works 


The mechanical seal uses two elements to keep the pumped item inside and avoid leakages. These include the two flat-lapped faces of the seal. However, one of these faces rotates with the shaft. It is known as rotary. 


The other face doesn't rotate with the shaft and is known as stationary. As both the flat lapped faces rub together, a fluid film is applied between these two faces so that the seal can be cooled and lubricated. The pumped fluid you have placed will weep between the two lapped faces. 


It will enter in the form of a liquid and will remain like that until it is vaporized. You have to remember that the mechanical seal will release minor amounts of vapor, no matter how amazing it is. So, your pumped fluid will always be lost in an incredibly small amount, even with the best design. 


The Seven Components of A Mechanical Seal 

There are seven unique components of a mechanical seal that make it what it is. These include:

• The seat (stationary)

• Sealing member (stationary)

• Rotating component

• Sealing member (rotary)

• Clamp ring

• Gland plate 

• Spring


Types Of Mechanical Seals 

Once you have considered everything, you need to choose from the different options available in the market. These include:


1) Pusher Seal 

Many people opt for pusher seals for a variety of applications. That is because it is designed in such a way that it pushes a secondary seal across the shaft for compensating for shaft movement. The secondary sea can either be a wedge, an o-ring, or any other type of equipment. 


2) Inside Seal 

The inside mechanical seal's rotary component is situated inside the chamber. When such a seal is used, pressure is placed on the outside diameter of the seal. If your pumped medium requires intense and high pressure, then an inside seal will be the ideal choice for you. 


mechanical seals application-2

3) Outside Seal 

The outside seal is the opposite of the inside deal. The rotary component of this seal is situated outside the chamber. This seal's main aim is that it doesn't allow the fluid to come in contact with the metallic components of the seal. That saves cost as you don't have to spend too much on costly materials. 


4) Double Seal 

A double seal is when two seals face each other, facing in the same direction, or back to back. This mechanical seal's main aim is to allow a gas or buffer fluid to be between the faces of the seal. They are best used for products that can change state, solidify, are volatile, viscous, non-lubricating, or dirty. 



Application of Mechanical Seals 

Here are the many uses that the mechanical seal can fulfill:

• Wastewater treating

• Thick liquid pumping

• Drainage well pumps

• High-pressure liquid pumping

• High-temperature liquid pumping

• Centrifugal pumps

• Abrasive pumps

• Self-priming pumps


The seal that is included between the rotating component and the seat is known as the primary seal. It serves the most important function, and it comes in various materials that include Alumina Ceramic, Tungsten Carbide, Carbon-Graphite, and Silicon Carbide. 


The choice of the material for the primary seal surface depends on the pumped liquid you need to seal. That is because it needs to withstand the temperature and pressure of the pumped liquid. So, keep these considerations in mind before selecting a material for your application. 


Top Things to Consider When Purchasing Mechanical Seals 


Before deciding to purchase a mechanical seal, you need to keep a few things in mind. These include: 


1) Dimensions 

You will need to understand each dimension before you purchase the mechanical seal. Take a note of the dimensions of the shaft, stationary components, and rotary components. Once that is done, don't forget to take out the working length of the seal. 


2) Operating Speed of The Shaft 

The shaft speed will impact the mechanical seal. If the speed is high, the surface needs to have a smoothness to avoid excessive wear on the seal. However, if the surface is too smooth, then the mechanical seal might underperform. You have to consider the surface and the speed before you decide to purchase a mechanical seal. 


mechanical seals application--3

3) Medium You Need to Pump 

The medium you will pump, or seal will directly impact the material you choose for the seal. That is because different mediums such as water, oil, chemicals, and semi-solids will impact the durability and wear tear of your seal. It would be best to choose a mechanical seal with the perfect material for your medium of choice. 


4) Pressure and Temperature 

The temperature will affect the type and material of the seal, and so will pressure. The amount of pressure applied against the rotating component is important in understanding the materials you should opt for. 




That was your complete guide to mechanical seals. If you are a beginner, then this is where you need to start. All of this information will help you find the best mechanical seal for your business's needs. Remember to choose the right materials, consider the different aspects of the entire process, and you will have chosen the perfect mechanical seal. 


Wendong is China famous mechanical seals distributor, providing professional mechanical seal knowledge and high-quality mechanical seal. If you have any needs, please contact us!



WenDong specializes in produce mechanical seals and custom mechanical seals solutions. By utilizing our extensive expertise, we can provide a complete solution to your challenge.

Chehe Industrial Park Shiqi Town Ningbo Zhejiang, China


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